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Aviation History
1928
1928 - 0019.PDF
JANUARY 12, 1928 THE NEW KOOLHOVEN LIGHT 'PLANE The F.K. 30 " Toerist " With Siemens Engine IN our issue of February 3, 1927, we published general arrangement drawings and a description of a new light monoplane designed by Mr. Frederick Koolhoven of Rijswijk, Holland. At the time, the machine had just been designed, and the work of construction had not been commenced. The machine has now been completed and has, we under- stand, been put through some of its flying tests. It may be recollected that one of these machines was ordered by- Mr. Clifford Harmon, President of the International League of Aviators, who intends to use it for visiting the various European posts of the League. The F.K. 30 is of very unusual design, and may be said to represent an attempt to combine the comfort and view of the old pre-war " pusher " type of machine with the aerodynamic efficiency of modern aircraft. Whether or not Mr. Koolhoven has succeeded in this aim cannot be said until complete test results are available, and some practical experience has shown how the machine behaves in regular use. That there will be minor " teething troubles " to get through is to be expected in a type which differs so materially from the normal. A comparison between the photograph published this week, which has just been received, and the general arrange- The fuselage and wing are both covered with three-ply, so that there should be no question of rigging or keeping in trim the machine during use. In the deep portion of the fuselage, under the engine mounting, is a large luggage compartment. The two seats are arranged in tandem, and dual controls are provided. The view is particularly good forward and down as there is neither engine nor wing in front to obstruct it. The high centre of thrust resulting from this unusual arrangement of the machine may be expected to have an effect on the trim according to whether the engine is running or not, but the same applies in large flying-boats, where the forces are much greater, and with proper design there is no reason to believe that this should give rise to any trouble. The slight loss in efficiency due to the down load on the tail probably does not amount to a great deal either, and if the advantages of the " pusher " can be attained without much sacrifice in performance or trim, they would be well worth having. The narrow and shallow rear portion of the fuselage is open to objection on the score that it will require to be comparatively substantially built so as to give the strength necessary to carry a tail mounted high above it, and in the slipstream of, and fairly close to, the THE NEW KOOLHOVEN MONOPLANE: Three-quarter front view of the F.K. 30 "pusher" with Siemens engine. ment drawings published in our February 3 issue, it will be observed that certain minor changes have been made since the original lay-out of the machine. These, however, are not of a nature to cause any fundamental changes in the design, which remains a parasol " pusher " semi-cantilever monoplane. Apart from the " pusher " arrangement, the Koolhoven F.K. 30 is remarkable on account of the " turntable " mounting of the wing and engine unit. This turntable, secured to the fuselage structure just below the engine, supports the whole superstructure. Normally, the turntable is locked in position with the wing " spread," but by undoing a quick-release the turntable can be rotated, bringing the wing into a fore-and-aft or " folded " position, the engine taking part in this rotation. With the wing " folded," the engine is outboard, and thus throws a load oil that side of the undercarriage, but as the wheel track is wide, there is probably little or no tendency for the machine to tilt over. From the photograph it will be noted that the wheels are somewhat " knock-kneed." At the moment it is not quite clear whether this is due to the shock absorbers not having been in place when the photograph was taken, or to too weak rubbers. At any rate, this position probably represents maximum travel, which in this machine is very large, something like one foot, as against the three or four inches more usuallv found on small machines. propeller. This feature, however, is Mr. Koolhoven's modern manner of getting away from the open tail girders of the old " pushers." To keep the machine small and compact, Mr. Koolhoven has had to use a fairly heavy wing loading, although a wing section of fairly deep camber helps to keep down the landing speed, which is claimed co be only about 40 m.p.h. There is no fuel in the fuselage, the petrol being contained in two tanks in the wing, one on each side some little distance out. As the engine is entirely exposed, there should be little or no risk of fire, especially as the pipes from the tank have been so arranged as to reduce to a minimum the consequences of a fractured pipe. The Koolhoven F.K. 30 shown in the photograph is fitted with a Siemens engine, but we gather that if desired it can be supplied with a " Genet " or other similar engine of approxi- mately the same power. The F.K. 30 weighs 330 kgs. (726 lbs.) empty, and carries a useful load of 300 kgs. (660 lbs.), giving a total loaded weight of 630 kgs. (1,386 lbs.). The useful load can be composed of pilot, passenger, 90 lbs. of luggage, and five hours' fuel, or, of course, any other combination giving the same total, such as more luggage and less fuel, and so forth. The packing case for the machine is constructed to be used as hangar and workshop. 19 c2
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